The standards of the legislators must be specified and adapted to the requirements of ePRO. Because the design of the tool surface and the rate of usability can influence the response behavior of the patients, the focus should be on the reliability and validity of ePRO surveys in the context of their implementation in relation to the patients, disease, questionnaire and ePRO-specific variables, which determine the response behavior, in order not to endanger the meaningfulness of PRO surveys.